1. Field of the Invention
The present invention relates generally to a multi-axes type robot which includes at least one arm unit having a plurality of pivotal axes. More specifically, the invention relates to a multi-axes type robot which has at least one arm unit comprising a pivotal base or shoulder member, a first pivotal arm pivotably supported on the shoulder member, and a second pivotal arm pivotably supported on the first pivotal arm at a free end thereof.
2. Description of the Prior Art
In recent years, various industrial robots have been used for processing various materials, such as the manufacturing of parts, or the assembling of apparatus. An example of such an industrial robot is a multi-axes type robot which includes an arm unit having a plurality of pivotal axes. Such a robot is basically comprised of a stationary base on which a mounting portion is mounted at a predetermined position, a first pivotal arm which is pivotably supported on the stationary base, a second pivotal arm which is pivotably supported on the free end of the first pivotal arm, a tool mounting shaft supported on the free end of the second pivotal arm and a drive mechanism for driving the tool mounting shaft.
In the assembly of an apparatus, various kinds of operations are usually performed on an assembly line. Therefore, if the different operations on the assembly line are performed by industrial robots, the line requires a plurality of robots. As a result, the overall length of the line becomes very long, and the installation cost thereof becomes very high.
In addition, although there is an advantage in that the aforementioned multi-axes robot can be compact, it is difficult to pre-mount a plurality of tools on the robot. Therefore, there are disadvantages in that the tool mounted on the robot must be changed whenever a line operation is altered, thereby reducing operating efficiency.
In order to overcome the aforementioned disadvantages, there has been proposed an improved, multi-arm type, multi-axes robot on which a plurality of tools can be mounted and which can tools can selectively or simultaneously be driven by the robot. This robot generally comprises an essentially cylindrical stationary base, and two arm units pivotably supported on the stationary base. Utilizing such a robot, the whole length of an assembly line can be reduced. However, since the respective arms are mounted on the stationary base at predetermined positions, the working range of each arm is fixed, meaning that the cooperative working range of the arms is fixed. Therefore, in a case where the working range of any of the arms or the cooperative working range between the arms needs to be changed in order to facilitate a change in line operation, another robot must be arranged on the line.